Generally, a vacuum insulation panel includes an encapsulant comprised of a composite plastic laminate film exhibiting good gas barrier properties, a core received in the encapsulant and comprised of a continuous bubble hard plastic foam or inorganic material, and gas barrier films stacked along the rim of the panel and heated to seal the panel after decompression of the panel.
Generally, a vacuum insulation panel allows air or moisture to pass through the encapsulant or carbon dioxide or other gas is generated therein, so that the degree of vacuum is gradually reduced over time to increase thermal conductivity, thereby making it difficult to maintain a high degree of insulation.
To solve such problems, a conventional vacuum insulation panel includes a core made of a mixture of an organic binder and glass fiber.
Further, as to the core of the vacuum insulation panel, a binder-free glass wool type core is prepared through heat compression without using a binder, or a binder glass wool type core is prepared through surface hardening with a binder.
The binder-free glass wool type core exhibits good initial thermal conductivity, but has insufficient long term durability due to an undulating surface formed upon processing of the vacuum insulation panel.
The binder glass wool type core has a flat surface, but exhibits low initial thermal conductivity and long term durability.
An outer cover for the vacuum insulation panel is generally made of a typical material for vacuum packaging, which has a laminate structure of a surface protective layer, a metal barrier layer and an adhesive layer.
The vacuum insulation pad is likely to undergo deterioration in performance due to cracking of the metal barrier layer at a folded portion of the outer cover upon processing of the vacuum insulation panel.
The getter is made of a material capable of absorbing only moisture or both gas and moisture, and serves to maintain the degree of vacuum within the vacuum insulation panel through absorption capability and the amount of the material provided.
As such, conventionally, vacuum insulation panels are manufactured using a binder-free glass wool type core or a glass wool type core subjected to surface treatment with an inorganic binder, an outer cover prepared by stacking an Al foil and an organic film, and getters capable of absorbing moisture and gas.
Such a conventional vacuum insulation panel has a lifetime of 8 years or less under conditions of 0.010 Kcal/mhr° C., causing low reliability not only in the field of buildings requiring a lifespan of 10 years or more, but also in the field of electronic appliances.